Mine roof support assemblies

ABSTRACT

Mineral mining installations provided with movable roof support assemblies at the stowage side of a conveyor with shifting rams connected between the conveyor and the assemblies. Each assembly has a number of extendible hydraulic props mounted between a floor sill and a roof cap. At the stowage side of the assembly there is provided a stowage shield composed of relatively pivotable components at least one of which has a U-shaped crosssection. The shield components are connected to a system of levers which control the movement of the components when the props are extended or retracted so as to continuously screen off the stowage zone from the assembly.

0 United States Patent 11 1 1111 3,830,070 Rosenberg et al. I Aug. 20,1974 MINE ROOF SUPPORT ASSEMBLIES 3,686,874 8/1972 Bell 61 45 1) [75]Inventors: Harry E. Rosenberg, Ludinghausen; FOREIGN PATENTS ORAPPLICATIONS Y Bockum'Hoveli 1,503,990 10/1967 France 61/45 D Lubomll'Pl va Aschenberg; 1,937,308 2/1971 Germany 61 45 D Kumbert Becker, Werl,all of 1,061,071 3/1967 Great Britain 61 /45 D Germany 1,815,585 4/1966U,S.S.R......... 61/45 D [73] Assigneez Gewerkscha Eisenhutte westfalia238,488 3/1969 U.S.S.R 61/45 D Westfaha Germany Primary Examiner-DennisL. Taylor [22] Filed: Oct. 2, 1972 Attorney, Agent, or Firm-Sughrue,Rothwell, Mion, 21 Appl. No.: 293,895 Macpeak o [57] ABSTRACT [30]Foreign Application Priority Data O t 2 1971 G 21 9380 Mmeral mmmginstallations provided w1th movable 1972 Germany 4 roof supportassemblies at the stowage side of a conmany 2217830 veyor with shiftingrams connected between the conveyor and the assemblies. Each assemblyhas a number of extendible hydraulic props mounted between a [58] Fi d299/31 1 floor sill and a roof cap. At the stowage side of the ase 0 can91/170 M sembly there is provided a stowage shield composed ofrelatively pivotable components at least one of which has a U-shapedcross-section. The shield components [56] References and are connectedto a system of levers which control the UNITED STATES PATENTS movementof the components when the props are ex- 3,324,664 6/ 1967 Allen 61/45 Dtended or retracted so as to continuously screen off 3,357,742 12/1967Dommann et al. 61/45 D X the stowage zone from the assembly. 3,483,70512/1969 Roberts 61/45 D 3,564,857 2/1971 v6 Hippel 61 45 1) 24 Claims, 8Drawing F gu es j w I L Till? A sum 1 or 4 PATENTEBwszo 1914 Fig/1 15PATENTEB M1820 m4 SHEET 2 OF 4 113 110 113 29 Flg. 4.

PATENTED 1112201914 SHEET 3 [IF 4 Fig.5.

F i g. 7.

MINE ROOF SUPPORT ASSEMBLIES BACKGROUND TO THE INVENTION SUMMARY OF THEINVENTION The invention provides a mine roof support assembly comprisinghydraulic props mounted between a floor sill and a roof cap and astowage shield composed of relatively pivotable components adapted inuse to screen off the stowage zone from the assembly when the props areretracted or extended.

There may be two shield components pivotably interconnected through ajoint which moves outwardly of the assembly when the props retract. Oneshield component may serve to cover or screen the space between the capand the floor sill from the stowage zone when the props are fullyretracted with the other shield component being contained within thefirst-mentioned component. When the props are extended, the shieldcomponents pivot out and combine to again screen off the aforesaidspace.

A support assembly made in accordance with the invention can provideconsiderable supporting strength and angular rigidity.

Preferably the stowage shield components are connected to control leverspivotably connected between the roof cap and the floor sill. In one formthere are three pivotably interconnected control levers, each of twolevers being connected to a respective shield component and a thirdlever being connected to the floor sill. These levers may adopt aZ-shaped side profile when the props are fully retracted.

In a particularly advantageous construction, an upper shield componentis pivotably connected at a joint to the roof cap, the control leversbeing such that when the props are extended or retracted the pivot jointmoves along a substantially vertical line. It follows that when theprops are extended or retracted there is no lateral forces which wouldotherwise tend to alter the inclination of the props. The control leversin this construction are each pivotably connected between said uppershield component and the floor sill. Preferably 'there are two sets oflevers, one set being disposed above the other, the pivot joints of eachset of levers being offset vertically and horizontally from the other,the lower set of levers having a plate constituting a lower component ofthe shield connected therebetween.

By making at least one of the pivot joints adjustable in a directionparallel to the floor sill, the angle of inclination of the props can bevaried, typically in the range 2 to 9 from the vertical. In oneconstructional embodiment employing such adjustment, a shifting ram canbe used to displace a common shaft forming two pivot joints.

Preferably the shield components, or at least one of these components,has a U-shaped cross-section. In this way the shield component canpartly surround the stowage side props of the assembly.

The floor sill of the assembly may be connected through a shifting ramto a conveyor or a troughsupport for the conveyor. Preferably guidebeams serve to guide the support assembly in relation to the conveyor.

The invention may be understood more readily and various other featuresof the invention may become more apparent from consideration of thefollowing description.

BRIEF DESCRIPTION OF DRAWINGS Embodiments of the invention will now bedescribed, by way of examples only, with reference to the accompanyingdrawings, wherein:

FIG. 1 is a side view of a mineral mining installation employing a roofsupport assembly made in accordance with the invention with the props ofthe assembly fully extended;

FIG. 2 is a plan view of the floor section of the assembly shown in FIG.1;

FIG. 3 is a side view of the assembly shown in FIG. 1 with the propsfully retracted;

FIG. 4 is a schematic side view of another support assembly made inaccordance with the invention;

FIG. 5 is a side view of a mineral mining installation employing anassembly represented schematically in FIG. 4 with the props of theassembly fully extended;

FIG. 6 is a side view of the assembly shown in FIG. 5 with the propsfully retracted;

FIG. 7 is a part-sectional plan view of the floor section of theassembly shown in FIGS. 5 and 6; and

FIG. 8 is a side view of a further installation employing a roof supportassembly made in accordance with the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring initially to FIGS. 1 to3, a roof support assembly is provided at the stowage or goaf side of ascraper chain conveyor 10 installed alongside the mineral face in a mineworking. The conveyor 10 is in known manner composed of channel sectionsarranged end-to-end, and a number of assemblies as illustrated would bedisposed alongside the conveyor 10. The assembly shown in FIGS. 1 to 3has a floor sill in the form of a torsionally rigid base frame 11 whichsupports four hydraulically operated props 12, 13 disposed in arectangular array as depicted in FIG. 2. Each prop 12, 13 is connectedto the frame 11 via a joint 14, preferably a universal joint, whichpermits the prop to tilt to a limited extent. The props l2, l3 bear aroof cap 15 at their upper ends, and the cap 15 has a scrap deflector 16at the stowage side and a forward or advance lining cap 17 at the faceside. The cap 17 is pivotably connected via a joint 18 to a toggle lever19 which in turn is pivotably connected via a joint 20 to the face endof the main cap 15. A hydraulic piston and cylinder unit 21 is pivotablyconnected between the lever 19 and the underside of the cap 15. The unit21 is operated to pivot the toggle lever 19 and raise or lower the cap17 in relation to the roof of the mine working. When the props 12, 13are set and the unit 21 actuated, the caps l5, 17 can contact the roofof the working over a large area. Further auxiliary caps (not shown) canbe provided on the sides of the main cap 15. These auxiliary caps can beextendible and retractable laterally so that the auxiliary caps ofadjacent support assemblies can more or less cover the area of the roofbetween the adjacent assemblies. In this way the entire roof can besupported, if desired, throughout the complete length of the working.The main cap also has guide plates 15 at its sides, and these plates 15'may guide and support an adjacent support assembly.

As mentioned, the props 12, 13 can tilt, and to bring the props 13 intothe desired orientation these props 13 are pivotably interconnected viaa yoke 22 and a hydraulic piston and cylinder unit 25 is pivotablyconnected to the yoke 22 and to the frame 11. Thus, the unit 25 can beused to tilt the props 13 about the joints 14.

The assembly is provided with a screen or shield for screening off andprotecting the assembly from the stowage material. This shield iscomposed of two relatively movable components denoted 30, 32 controlledwith levers 26, 27, 28. The levers 26, 27, 28 may be rigid plates orframes. The upper lever 26 is pivoted at its upper end to a joint 29provided on the underside of the cap 15 between the props 12, 13. Theupper end of the intermediate lever 27 is pivotably connected to thelower end of the lever 26 by means of a joint 31. Similarly the lowerlever 28, which is somewhat shorter than the levers 26, 27, has itsupper end pivotably connected to the lower end of the lever 27 via ajoint 33. The lower end of the lever 28 is pivotably connected to ajoint 35 provided on a plate or similar projection 34 of the base frame11.

The upper shield component 30 is rigidly connected to the lever 26 andhas a U-shaped profile with its open side directed towards the face ofthe working. The main wall of the component 30 has slots therein foraccommodating the rear props 13 and is approximately the same width asthe main cap 15. The sidewalls of the component 30 have inclined outeredges 30' and recesses 39 in their lower edges adjacent the main wall.The lower shield component 32 is rigidly connected to the lever 27 andalso has a U-shaped profile with its open side directed towards the faceof the working. The main wall of the components 32, designated 36, isagain about the same width as the cap 15 but slightly larger than thatof the component 30. The sidewalls of the component 32 have atrapezoidal configuration, and the component 30 has a narrow lowerportion snugly received within the component 32 when the props 12, 13are set as depicted in FIG. 1 to provide a composite inclined shield inrespect of the goaf or stowage material. In this position with the props12, 13 set, the levers 26, 28 are inclined in relation to the axis ofthe props 12, 13, whereas the lever 27 is substantially parallel to theprop axis. In the vicinity of the joint 29, the cap 15 has on itsunderside a bracket 37 which engages the lever 26 when the props 12, 13are fully extended and thereby acts as a stop member to prevent thelever 26 from pivoting to displace the joint 31 towards the mineralface. When the props 12, 13 are retracted, the shield component 30pivots into the component 32 as the joint 31 moves in the direction ofarrow A in FIG. 1 and the joint 33 moves in the direction of arrow B.When the props 12, 13 are fully retracted, as shown in FIG. 3, the lever26 adops a near horizontal position and the levers 26, 27, 28 present aZ-shaped side profile. In this position solely the wall 36 of thecomponent 32 serves to screen off the stowage material. The spacebetween the front and rear props 12, '13, respectively, is essentiallyunimpeded by the components 30, 32. The control lever carries a stopmember in the form of a pin 38 or the like which engages in the recesses39 in the sidewalls of the shield component 30 when the props 12, 13 arefully retracted as shown in FIG. 3.

The base frame 11 has lugs 40 on the side facing the a conveyor 10. Thelugs 40 bear pins pivotably locating projections 41 connected to thelower part of the associated channel section of the conveyor 10. Theprojections 41 may be, alternatively, resiliently connected to the frame11. The conveyor 10 rests on a trough-like support 42. The conveyor 10may move to a limited extent on the support 42, or a locking device mayclamp the conveyor channel sections to the support 42. In known mannerthe support 42 carries a guide 43 on its face side for a plough or thelike. The conveyor 10 is not itself directly subjected to shiftingforces and accordingly the sections of the conveyor 10 can belightweight components. Barrier plates 44 are attached to the stowageside of the conveyor 10 as well as guides 45 again for the plough or thelike. The support 42 has beams 46 rigidly secured thereto. Each beam 46,as shown in FIG. 2, extends between two adjacent support assemblies andacts as a guide means to mutually align the assemblies and the supports42. The frame 11 has a bracket 51 which is pivotably connected, at joint50, to the piston rod 49 of a shifting ram 47. The ram 47 has itscylinder connected, via a vertically movable connection 48 to thesupport 42. The ram 47 can thus effect relative movement between thesupport assembly and the support 42 with its associated section orsections of the conveyor 10. The rams 47 would be used to advance theconveyor 10 or the support assem blies towards the mineral face. Thesupport assemblies can be shifted under load with their caps 15 onlypartly lowered. The aforesaid beams 46 and guide plates 15' serve toalign the assemblies and the conveyor 10 during shifting.

Referring now to FIGS. 4-7 a roof support assembly has a floor sill andfour props 112 each connected to the sill 110 with a ball and socketjoint 113. A roof cap 111 is similarly connected to the props 112 withball and socket joints 114. A forward lining cap 115 is pivotablyconnected to the front end of the cap 111 and a piston and cylinder unit116 is connected between the caps 111, 115 to enable the cap 115 to beraised and lowered in relation to the roof. A goaf screen or shield 118is pivotably connected via joints 119 to the stowage end 111 of the cap111. The shield 118, which has a U-shaped cross-section with a main wallfacing the stowage zone and two sidewalls, surrounds the stowage-sideprops 112. Two sets of control levers 120, 121 are operably connected tothe shield 118. The upper levers 120 are pivotably connected to theshield 118 via joints 123 and to side panels 129 of the floor sill 110via joints 122. The lower levers 121 are pivotably connected to theshield 118 via joints and to the panels 129 of the floor sill 110 viajoints 124. With the props 112 fully extended as illustrated in FIG. 4,the sets of levers 120, 121 converge towards the roof above the stowagezone and extend at an angle in the region of 50 70 in relation to thefloor of the working. The joints 122, 123 are disposed above the joints124, 125, respectively. The joints 119, 123 and 125 lie on a common lineX. The main stowage wall of the shield 118 is formed of a lower portionco-planar with the outside of the levers 121 and an upper portioninclined in relation to the lower portion. The juncture between theportions of the stowage wall is denoted 118.

When the props 112 are retracted the levers 120, 121 pivot so that thejoints 123, 125 move towards the stowage zone. The control levers 120,121 and associated joints form a lemniscale" guide system since each ofthe joints 119 moves along an almost planar vertical curve y. Thisensures that the inclination of the props 112 denoted Z does not alterwhen the props are retracted or extended. The shield 118 and the levers120, 121 provide angular rigidity to the assembly to ensure that theassembly will not tilt when subjected to forces from the stowage zone orroof. The angular position of the props 1 12, i.e., Z, can be varied byadjusting the position of the joints 122 in a direction parallel to thefloor. To this end the levers 120 are connected to a common shaftconstituting the joints 122, and this shaft is displaceable in slots 129in the panels 129 by means of an adjusting device 122 which may be amechanical screw type device or a hydraulic device. The slots 129' areof such length as to enable the props 112 to form an inclined Z of from2 to 9 in relation to the vertical V.

FIGS. 5 to 7 depict a mining installation employing roof supportassemblies of the type generally described in connection with FIG. 4 andlike reference numerals denote like parts in FIGS. 4-7. As shown theprops 112 each have two extendible parts or stands 112", 112'. It isadvisable to make the props 112 on the stowage side retractablehydraulically, i.e., the so-called robbing aid. Thus when the props 112retract the cap 111 pivots about the joints 114 of the face side props112. If the cap 111 or 115 fails to find adequate contact with the roof,where for example fractures occur, the rear or stowage side props 112can be relieved hydraulically to tilt the front end of the cap 111upwardly to provide a better supporting contact. When the props 112 areretracted to lower the cap 111, the levers 120, 121 pivot with theshield 118 so that the joints 119 move along an almost vertical pathwhile the joints 123, 125 move along intersecting arcuate paths K, K2 inFIG. 5. When the props 112 are fully retracted, the shield 118 and thelevers 120, 121 take the position shown in FIG. 6 with the shield 118covering the entire space between the cap 111 and the floor sill 110.The levers 121 are interconnected via a shield plate 128 at the stowageside which is substantially co-planar with the lower portion 118' of theshield 118 to screen off the stowage space when the props 112 are fullyextended. The side panels 129 of the floor sill 110 extend upwardly toabout the upper end of the base part of the props 112 and lie within thesidewalls of the shield 118 so as to form a substantially continuousside cover with these sidewalls when the props 112 are set.

A shifting ram 117 has a piston rod 130 with a bifurcated end pivotablyconnected at a joint 134 to a plate 131 in turn connected to the centreof a shaft 126. The shaft 126, which also forms the joints 122, issupported in slots in brackets 127 of the floor sill 110 to form athrust bearing for the ram 117. The shaft 126 is displaceable parallelto the floor to vary the inclination of the props 112. The actualdisplacement of the shaft 126 can be effected by means of the ram 117and detachable clamping means, such as wedges or bolts, can be used tosecure the shaft 126 in any desired position commensurate with someinclination of the props. The clamping means would be operated torelease the shaft 126 so that it can be moved by the ram 117 wheneverthe inclination of the props 112 is to be altered.

The cylinder of the ram 117 is connected via a shackle with a pivot pin132 to a connecting piece 133 having a slidable bushing 135 located on arail 136. The rail 136 is connected to the stowage face side of theassociated channel section or sections of a conveyor 137. At either sideof the connection between the rail 136 and the ram 117 there is provideda tapered guide beam projecting at one side of the associated supportassembly. The beams 140 are connected to the rail 136 via similarconnections to that of the ram 117, the pivot pins being denoted 138 andthe slidable bushing 139. The beams 140 serve to guide the supportassemblies.

Hydraulic piston and cylinder units 141 used to tilt the conveyor 137are connected between the rail 136 and a floor support. The conveyor 137has guide ramp l44 at the mineral face side which supports and guides aplough 142. By operating the units 141 the conveyor 137 can be tiltedabout the floorengaging edge 143 of the ramp 144 to adjust the cuttingpath of the plough 142.

Another installation employing a further type of roof support assemblyis depicted in FIG. 8 and like reference numerals denote like parts tothose shown in FIGS. 4 to 7 and described above. In the constructionshown in FIG. 8, the props 112 have a single extendible stand. As beforethe control levers 120 are connected to the joints 122 provided on sidepanels 129 of the floor sill 110, but the corresponding joints 124 forthe levers 121 are provided on brackets extending upwardly from thefloor sill 110. The means for adjusting the position of the joints 120is not illustrated. The floor sill 110 has projections directed towardsthe mineral face which are slidably guided on their inner faces by twoparallel guide beams 156. These beams 156, which extend beneath theconveyor 161, are rigidly interconnected with a baseplate 157 whichcarries two hollow bars 158, 159, in turn interconnected by a web 160extending parallel to the baseplate 157. The web 160 and the bars 158,159 form a trough support into which the associated channel section orsections of the conveyor 16] is received. The sections of the conveyor161 can, as is known, be lightweight components. The conveyor section orsections may move in relation to the trough support 160, 158, 159 or beclamped thereto. To this end cover plates 162, 163 are secured withscrews onto the bars 158, 159 to engage over the sides of the channelsection(s) and form guides for the scrapers of the conveyor. A mineralcutting machine 164 can be supported on the plates 162, 163 and a ploughcan be supported on a guide ramp 165 and the bar 162. The shifting ram117 has its piston rod 130 pivotably attached, at a joint 166, to thebar 159 and the cylinder of the ram is connected to the floor sill 110.By extending the rod 130 the components l56-l65 can be moved towards theface and guided by the projections 1 55, and by retracting the rod 130the floor sill 110 and the remainder of the support assembly can bedrawn up and guided on the beams 156.

We claim:

1. In a mine roof support assembly comprising hydraulically extendibleprops mounted between a floor sill and a roof cap, the improvementcomprising a novel stowage shield composed of relatively pivotablecomponents for screening off the assembly from the stowage zone whetherthe props are extended or retracted, said novel stowage shieldcomprising:

l. a first shield component pivotably connected to the roof cap at firstpoints thereon for rotational movement in the longitudinal direction ofthe assembly;

2. a first pair of parallel control levers pivotably connected to saidfirst shield component at second points thereon and to the floor sill atthird points thereon in a manner permitting said first pair of parallelcontrol levers to rotate about said third points in the longitudinaldirection of the assembly;

3. a second pair of parallel control levers disposed beneath said firstpair of parallel control levers, said second pair of parallel controllevers being pivotably connected to said first shield component atfourth points thereon which are offset vertically and longitudinallyfrom said second points and to the floor sill at fifth points thereonwhich are offset vertically and longitudinally from said third points ina manner permitting said second pair of parallel control levers torotate about said fifth points in the longitudinal direction of theassembly; and

4. a second shield component connected between said second pair ofparallel control levers.

2. A mine roof support assembly as claimed in claim 1 wherein thehydraulically extendible props are mounted at an angle to the vertical,but the relation of said first shield component to said first and secondpairs of parallel control levers is such that said first points movealong a near vertical line as the props extend or retract.

3. A mine roof support assembly as claimed in claim 1 wherein said firstpoints, said second points, and said fourth points lie on common linesin side view when the props are fully extended.

4. A mine roof support assembly as claimed in claim 1 wherein at leastone of said third and said fifth points is adjustable longitudinally ofthe assembly to vary the inclination of the props.

5. A mine roof support assembly as claimed in claim 1 wherein at leastone of said third and said fifth points is joined by a common shaftdisplaceable in a direction substantially parallel to the floor sill tovary the inclination of the props.

6. A mine roof support assembly as claimed in claim 5 and furthercomprising means for adjusting the position of said common shaft to varythe inclination of the p 7. A mine roof support assembly as claimed inclaim 1 wherein said fourth points move outwardly of the assembly whenthe props retract.

8. A mine roof support assembly as claimed in claim 1 wherein at leastone of said first and second shield components is of U-shapedcross-section with its open side facing inwardly of the assembly.

9. A mine roof support assembly as claimed in claim 1 and furthercomprising at least one hydraulic piston and cylinder unit for varyingthe inclination of at least one of the props.

10. A mine roof support assembly as claimed in claim 1 and furthercomprising:

1. an advance lining cap pivotably connected to the roof cap and 2.means for raising and lowering said advance cap.

11. A mine roof support assembly as claimed in claim 1 wherein saidfirst and second pairs of parallel control levers converge towards theroof of the stowage zone.

12. A mine roof support assembly as claimed in claim 11 wherein saidfirst and second pairs of parallel control levers extend at an angle inthe region of 5070 in relation to the floor sill when the propsar efully extended.

13. A mine roof support assembly as claimed in claim 1 wherein saidfirst and second pairs of parallel control levers extend at an angle inthe region of 50-70 in relation to the floor sill when the props arefully extended.

14. In a mine roof support assembly comprising hydraulically extendibleprops mounted between a floor sill and a roof cap, the improvementcomprising a novel stowage shield composed of relatively pivotablecomponents for screening off the assembly from the stowage zone whetherthe props are extended or retracted, said novel shield comprising:

1. a first shield component pivotably connected to the roof cap at firstpoints thereon for rotational movement in the longitudinal direction ofthe assembly;

2. first and second pairs of parallel control levers pivotably connectedto said first shield component at second and fourth points thereon,respectively, and

to the floor sill at third and fifth points thereon, re-

spectively, in a manner permitting said first and second pairs ofparallel control levers to rotate about said third and fifth points,respectively, in the longitudinal direction of the assembly;

3. a second shield component connected between said second pair ofparallel control levers; and

4. means for adjusting at least one of said third and said fifth pointslongitudinally to vary the inclination of the props.

15. A mine roof support assembly as claimed in claim 14 wherein thehydraulically extendible props are mounted at an angle to the vertical,but the relation of said first shield component to said first and secondpairs of parallel control levers is such that said first points movealong a near vertical line as the props extend or retract.

16. A mine roof support assembly as claimed in claim 14 wherein saidfirst points, said second points, and said fourth points lie on commonlines in side view when the props are fully extended.

17. A mine roof support assembly as claimed in claim 14 wherein saidmeans for adjusting at least one of said third and said fifth pointslongitudinally to vary the inclination of the props comprises a commonshaft displaceable in a direction substantially parallel to the floorsill.

18. A mine roof support assembly as claimed in claim 17 and furthercomprising means for adjusting the position of said common shaft.

19. A mine roof support assembly as claimed in claim 14 wherein at leastone of said second and fourth points moves outwardly of the assemblywhen the props retract.

20. A mine roof support assembly as claimed in claim 14 wherein at leastone of said first and second shield components is of U-shapedcross-section with its open side facing inwardly of the assembly.

21. A mine roof support assembly as claimed in claim 14 and furthercomprising:

1. an advance lining cap pivotably connected to the roof cap and 2.means for raising and lowering said advance cap.

22. A mine roof support assembly as claimed in claim 14 wherein saidfirst and second pairs of parallel control levers converge towards theroof of the stowage zone.

23. A mine roof support assembly as claimed in claim 22 wherein saidfirst and second pairs of parallel contended.

1. In a mine roof support assembly comprising hydraulically extendibleprops mounted between a floor sill and a roof cap, the improvementcomprising a novel stowage shield composed of relatively pivotablecomponents for screening off the assembly from the stowage zone whetherthe props are extended or retracted, said novel stowage shieldcomprising:
 1. a first shield component pivotably connected to the roofcap at first points thereon for rotational movement in the longitudinaldirection of the assembly;
 2. a first pair of parallel control leverspivotably connected to said first shield component at second pointsthereon and to the floor sill at third points thereon in a mannerpermitting said first pair of parallel control levers to rotate aboutsaid third points in the longitudinal direction of the assembly;
 3. asecond pair of parallel control levers disposed beneath said first pairof parallel control levers, said second pair of parallel control leversbeing pivotably connected to said first shield component at fourthpoints thereon which are offset vertically and longitudinally from saidsecond points and to the floor sill at fifth points thereon which areoffset vertically and longitudinally from said third points in a mannerpermitting said second pair of parallel control levers to rotate aboutsaid fifth points in the longitudinal direction of the assembly; and 4.a second shield component connected between said second pair of parallelcontrol levers.
 2. a first pair of parallel control levers pivotablyconnected to said first shield component at second points thereon and tothe floor sill at third points thereon in a manner permitting said firstpair of parallel control levers to rotate about said third points in thelongitudinal direction of the assembly;
 2. A mine roof support assemblyas claimed in claim 1 wherein the hydraulically extendible props aremounted at an angle to the vertical, but the relation of said firstshield component to said first and second pairs of parallel controllevers is such that said first points move along a near vertical line asthe props extend or retract.
 2. means for raising and lowering saidadvance cap.
 2. first and second pairs of parallel control leverspivotably connected to said first shield component at second and fourthpoints thereon, respectively, and to the floor sill at third and fifthpoints thereon, respectively, in a manner permitting said first andsecond pairs of parallel control levers to rotate about said third andfifth points, respectively, in the longitudinal direction of theassembly;
 2. means for raising and lowering said advance cap.
 3. asecond shield component connected between said second pair of parallelcontrol levers; and
 3. A mine roof support assembly as claimed in claim1 wherein said first points, said second points, and said fourth pointslie on common lines in side view when the props are fully extended.
 3. asecond pair of parallel control levers disposed beneath said first pairof parallel control levers, said second pair of parallel control leversbeing pivotably connected to said first shield component at fourthpoints thereon which are offset vertically and longitudinally from saidsecond points and to the floor sill at fifth points thereon which areoffset vertically and longitudinally from said third points in a mannerpermitting said second pair of parallel control levers to rotate aboutsaid fifth points in the longitudinal direction of the assembly; and 4.a second shield component connected between said second pair of parallelcontrol levers.
 4. A mine roof support assembly as claimed in claim 1wherein at least one of said third and said fifth points is adjustablelongitudinally of the assemblY to vary the inclination of the props. 4.means for adjusting at least one of said third and said fifth pointslongitudinally to vary the inclination of the props.
 5. A mine roofsupport assembly as claimed in claim 1 wherein at least one of saidthird and said fifth points is joined by a common shaft displaceable ina direction substantially parallel to the floor sill to vary theinclination of the props.
 6. A mine roof support assembly as claimed inclaim 5 and further comprising means for adjusting the position of saidcommon shaft to vary the inclination of the props.
 7. A mine roofsupport assembly as claimed in claim 1 wherein said fourth points moveoutwardly of the assembly when the props retract.
 8. A mine roof supportassembly as claimed in claim 1 wherein at least one of said first andsecond shield components is of U-shaped cross-section with its open sidefacing inwardly of the assembly.
 9. A mine roof support assembly asclaimed in claim 1 and further comprising at least one hydraulic pistonand cylinder unit for varying the inclination of at least one of theprops.
 10. A mine roof support assembly as claimed in claim 1 andfurther comprising:
 11. A mine roof support assembly as claimed in claim1 wherein said first and second pairs of parallel control leversconverge towards the roof of the stowage zone.
 12. A mine roof supportassembly as claimed in claim 11 wherein said first and second pairs ofparallel control levers extend at an angle in the region of 50*-70* inrelation to the floor sill when the props are fully extended.
 13. A mineroof support assembly as claimed in claim 1 wherein said first andsecond pairs of parallel control levers extend at an angle in the regionof 50*-70* in relation to the floor sill when the props are fullyextended.
 14. In a mine roof support assembly comprising hydraulicallyextendible props mounted between a floor sill and a roof cap, theimprovement comprising a novel stowage shield composed of relativelypivotable components for screening off the assembly from the stowagezone whether the props are extended or retracted, said novel shieldcomprising:
 15. A mine roof support assembly as claimed in claim 14wherein the hydraulically extendible props are mounted at an angle tothe vertical, but the relation of said first shield component to saidfirst and second pairs of parallel control levers is such that saidfirst points move along a near vertical line as the props extend orretract.
 16. A mine roof support assembly as claimed in claim 14 whereinsaid first points, said second points, and said fourth points lie oncommon lines in side view when the props are fully extended.
 17. A mineroof support assembly as claimed in claim 14 wherein said means foradjusting at least one of said third and said fifth pointslongitudinally to vary the inclination of the props comprises a commonshaft displaceable in a direction substantially parallel to the floorsill.
 18. A mine roof support assembly as claimed in claim 17 andfurther comprising means for adjusting the position of said commonshaft.
 19. A mine roof support assembly as claimed in claim 14 whereinat least one of said second and fourth points moves outwardly of theassembly when the props retract.
 20. A mine roof support assembly asclaimed in claim 14 wherein at least one of said first and second shieldcomponents is of U-shaped cross-section with its open side facinginwardly of the assembly.
 21. A mine roof support assembly as claimed inclaim 14 and further comprising:
 22. A mine roof support assembly asclaimed in claim 14 wherein said first and second pairs of parallelcontrol levers converge towards the roof of the stowage zone.
 23. A mineroof support assembly as claimed in claim 22 wherein said first andsecond pairs of parallel control levers extend at an angle in the regionof 50*-70* in relation to the floor sill when the props are fullyextended.
 24. A mine roof support assembly as claimed in claim 14wherein said first and second pairs of parallel control levers extend atan angle in the region of 50*-70* in relation to the floor sill when theprops are fully extended.